A wide variety of sensors are used in railroad settings. These sensors and illustrative applications include: wheel detectors, which are often used in railway operation to monitor train traffic; accelerometers, which can be used to detect impacts of flat wheels; strain gauges, which can be used to measure an amount of strain placed on a rail due to a passing rail vehicle; microphones, which can be used to detect the sound of worn bearings; heat detectors, which can be used to identify locations of abnormal amounts of friction; and the like. A typical rail main line can have thousands of miles of track circuits run for signaling and for track integrity/continuity detection (i.e., detecting a break in the track).
To date, wheel detectors, and most other types of sensors, need to be supplied with electrical current and connected to a controller or another form of processing hardware to utilize the capabilities of the sensors. In a typical rail yard, many hundreds of yards of wiring need to be run from the various sensors to control or data processing hardware to implement a rail yard monitoring/automation system. Such wiring substantially increases the installation and maintenance costs for such a system.